Structural documentation languages have been developed in which certain interpreting instructions can be used to define how information contained in a document should be presented on the display of a device. Some structural documentation languages to be mentioned in this context include HTML (Hypertext Mark-up Language) and XHTML (Extensible HTML). A document complying with such a structural documentation language comprises, in addition to the actual information to be presented, interpreting instructions, by means of which a device processing the document can compose the desired information. The interpreting instructions may include information, for example, about the font, character size, colour, italizing, bolding, etc. to be applied when displaying a text. Furthermore, the interpreting instructions may contain information about the background colour, the margins, the layout of the text, the line division, etc. The document may also contain a reference (a hyperlink) to another document, wherein pointing at the reference will start the downloading of the reference document and displaying it on the device. Typically, the interpreting instructions of the above-presented kind are separated from the rest of the text with delimiters, such as angle brackets <, >. Thus, the device which processes the document can distinguish the interpreting instructions from other information and act accordingly.
The use of structural documentation languages has significantly increased as the use of the Internet data network has spread worldwide. Thus, a majority of documents in the Internet data network has been implemented with a structural documentation language, typically with said HTML. In the early days of using the Internet data network, the only way to access documents in the Internet data network was, in practice, to use a desktop computer (desktop PC). In such computers, the monitor is relatively large in size, normally at least 14 inches. This is one reason why most of the documents in the Internet data network have been designed to be displayed with such a display device. Recently, however, there has also been a significant increase in the use of portable devices to view documents in the Internet data network. For example, mobile stations have been developed which comprise facilities, such as a WAP browser, for access to the Internet data network. In mobile stations, however, the size of the display is significantly smaller than the display size in monitors for desktop computers. This means that it is difficult to view a document designed for a large-size monitor with a compact display device of a mobile station. For example, the browsing of wide pages requires the scrolling of the display in the width direction and in the vertical direction. In such a situation, it is difficult to piece together the text e.g. for the reason that the user of the mobile station only sees a small part of the text lines at a time. Another possibility to display a wide page is to display the text lines of the original document on several lines one below the other. Also in this case, it may be difficult to piece together the text. Furthermore, when a text is displayed in table format, the division of the table in lines and columns may be distorted, wherein it is difficult or even impossible to find out which information belongs to a given line and column. For example, time tables are typically drawn up in such a table form.
In some cases, the compiler of the document has provided such a version of the document which has been optimized for a small display, to be more applicable for displaying on e.g. a mobile station.
Also, arrangements have been developed, in which the browser program to be used for displaying the document optimizes the document to be more suitable for the display device of the device at the stage of downloading. Such a browser program can be installed in e.g. a mobile station with a facility for the downloading of documents from a data network and for displaying them on the display of the mobile station. One problem in such an arrangement is that after the optimization, the layout of the document may no longer be as definite as the original document. The optimizing algorithm may also change such parts in the document which would be clearly visible even without the optimization. In such a situation, the user may manually switch off the optimization. FIG. 1a shows an example of a document which is designed to be shown on small-size displays. In FIG. 1b, the example document of FIG. 1a has been optimized by an optimizing algorithm of prior art, wherein it is clearly visible that in this case, the optimization impairs the clarity of the document.